1. Field of the Invention
The invention relates to a process and an apparatus for regulating traffic.
2. Background Information
Portable light signal equipment is already known which is used for regulating traffic at restricted points or as a replacement for defective stationary equipment. Frequently, it is observed that moveable traffic lights of this kind--which are required at building sites, for example--are frequently not optimally adapted to the traffic flow, for reasons of time, and as a result cause unnecessary delays to much of the traffic, particularly when the traffic flow is fluctuating.
Of the conventional portable light signalling equipment there is equipment without any feedback system which operates with extremely accurate quartz oscillators as the time base. The stop, go and clearance times are strictly programmed and are usually only very broadly adapted to the actual traffic and are invariable in their daily operation.
Centrally controlled and monitored equipment with passive light signalling equipment allows the signal to be set by feedback. However, they do require expensive cables the size of which has to be adapted to the power to be transmitted (including the current supply to the lights).
From DE-A-1813336 an apparatus for controlling two traffic lights is known, in which axle counters are provided which will switch the apparatus over by means of counters whenever there is a coincidence between two counting circuits, i.e. when the number of the counted vehicles leaving the restricted area has reached the number of the vehicles which entered this area. However, there is the problem that these numbers are different if vehicles remain in the restricted area or enter the restricted area from this point. In this case, the equipment has to be switched off. Moreover, this equipment does not provide separate go and clearance times.
In a process for adapting the function of traffic lights to the traffic flow, as known from FR-A-2359451, the green phases of a traffic light apparatus are adapted to the number of vehicles passing, the phases being extended as the number of vehicles passing the equipment during one phase increases. However, once again, no distinction is made between go and clearance times.